Professional audio systems are used in stadiums or halls with tiered seating that hold sporting events, concerts and the like. These audio systems typically comprise a number of loudspeaker cabinets that are hung from the stadium ceiling above and around the seating area, generally in a number of vertical arrays in order that all of the spectators receive relatively consistent audio volume and quality irrespective of their location within the stadium. Generally, the loudspeaker cabinets in each array are positioned at various angles with respect to the vertically adjacent loudspeaker cabinets in the array in order to focus the sound field as directly as possible towards the spectators in the tiered seating below. In many stadiums this will generally result in a curved or “J” shaped vertical array.
After the initial installation of a vertical array of speakers, it is generally difficult to adjust the various angles between loudspeaker cabinets in a hanging system due to the significant weight of the cabinets and the inaccessibility of the cabinets when they are hanging in mid-air. In many stadiums or halls, an array of speaker cabinets may be anywhere from 20-200 feet above the seating. As such, many loudspeaker systems require the angle of each loudspeaker cabinet to be calculated and manually adjusted prior to the cabinets being hung. These calculations and adjustments can be difficult and time-consuming, as they require the details of the stadium, the use of prediction software, and sufficient time in advance to calculate and prepare the loudspeaker cabinets for hanging. There may also be errors in the calculation, unaccounted for variables, and/or a lack of information that causes the sound field of the speakers after hanging to be less than optimal. This may result in inferior sound dispersion, as it is unlikely that the speakers will be taken down and re-adjusted due to the difficulty and time required to do so.
A review of the prior art reveals different designs of speaker hanging systems that provide various features to the designers and operators of speaker arrays. For example, U.S. Pat. No. 8,170,263 describes a rigging system that can rigidly maintain the angles between speakers in a line array, however the angles must be manually adjusted prior to suspension.
There are some loudspeaker systems that can be manually adjusted after they have been hung, as described in U.S. Pat. Nos. 7,216,180 and 5,819,959. However there are disadvantages to these systems as it can be very difficult to access the loudspeaker systems while they are hanging in order to adjust the speaker angles. There is also a safety concern in adjusting the speakers, as adjustment typically requires a worker to manually connect small moving parts located on very heavy columns of speakers, and the worker's fingers are often at risk of getting crushed. Furthermore, these systems often require the speaker angle to be grossly adjusted prior to hanging and then fine-tuned after hanging. Adjusting the speaker angles on more than one occasion during the set-up process can be time-consuming and inefficient, and still requires a prediction of the optimal speaker angle.
There are also loudspeaker systems that enable the angle of the loudspeaker cabinets to be adjusted remotely while the cabinets are hanging, for example as described in U.S. Pat. Nos. 6,652,046; 7,706,558; and US Patent Publication No. 2006/0169530. These systems generally have a hinge or pivot point connecting the front side of adjacent cabinets, and a pair of actuators located at the rear of each cabinet. There are several disadvantages to this type of set-up due to the weight distribution of a typical vertical speaker array. Specifically, the curved or “J” shaped fashion of an installed vertical speaker array results in the center of gravity of the array being moved rearward, thereby placing the largest fraction of the overall weight of the system supported by the rear rigging connections. In some cases, all of the speakers' weight is transferred through the rear rigging connection. This can be significant as a typical large scale loudspeaker array can contain up to 24 speakers generally weighing around 225 lbs (˜100 kg) each, creating a total speaker array weight of approximately 5400 lbs (˜2400 kg) in total weight. Prior art systems typically place the actuators at the rear of each cabinet, such that the actuators are the main connection link between adjacent cabinets. If a pair of actuators is used to support a 5400 lb (2400 kg) array, each actuator would typically need to be rated to carry 13,500 lbs (6100 kg) in order to meet the general industry safety regulations that require a 5:1 ratio for supporting an overhead load (5400 lbs/2 actuators multiplied by 5). An actuator rated to carry 13,500 lbs. would generally exceed the limits of an economically viable actuator that would be sized appropriately. As such, the prior art systems having an adjustable connection at the rear of the speaker cabinets would typically only be able to be adjusted when there is no load on the system.
Other prior art systems teach a variety of generally adjustable speaker systems, including U.S. Pat. Nos. 6,215,883; 6,792,117; US Patent Publication No. 2010/0158287; and U.S. Pat. No. 5,418,338. However these speaker systems are not directed to a hanging array of stadium loudspeakers and do not address the specific problems described above.
As such, there is a need for a loudspeaker system wherein the angle between vertically adjacent loudspeaker cabinets can be remotely adjusted after the loudspeaker system is hanging. There is a further need for a loudspeaker system wherein the load on the actuator is reduced in order to improve the safety of the system and make it more economically viable.